Add mediaqueries support

[csaunier]

Hello,

In case of a personnal project, i had to use some shapes in mediaqueries but the polyfill throw an error and it appear it was not handled. It's also #10 issue.

So here it is :)

I've wrote a demo file : demos/mediaQueries-demo.html

[lmclister]

@csaunier thank you for submitting this PR. Our contributor's license agreement system seems to have run a foul, so we will see if we can get it back up.

From briefly glancing at the PR, it looks like parts of it have come from other projects, which may make it difficult for us to accommodate it. Could you possible add a list of other other projects where code for this PR came from?

[csaunier]

@lmclister indeed, i use some parts of only one another projet, Repond.js (https://github.com/scottjehl/Respond).

More specifically, i use 4 of his regexp (one that strip comment, one that split on @media, two to get minwidth and maxwidth), and his method that return the value of 1em in pixels